Study on evaluation method of benefits from pollen forecast and service is significant for understanding public value of special weather forecast and service and potential benefits. Main estimating method used here is that pollen prediction accuracy(Af), time efficiency of service (Tf), percentage of information coverage(Ic)and prevention capability of pollinosis sufferers (P)， which are the important elements influencing how much the benefits is, are firstly designed to be as four factors of service benefits. Secondly， it is necessary to assess them and get four values calculated by monitoring pollen data from 2000 to 2006, pollinosis cases and investigating data coming from 146 questionnaires answered by allergy & clinical immunology experts and pollinosis sufferers in Tianjin. A mathematical estimating model of benefit coefficient, E=Af×Tf×Ic×P, is built based on the relationship between four factors mentioned above. Then the benefit from pollen forecast and service is figured out through the equation. Evaluation result shows that mathematical estimating model is practical and rational. And the value of total social benefits is remarkable.